Pusher-type chain conveyors, as used in the mining industry, are found both in the form of separate conveying units, and as integral parts of continuous mining machines. One example of a continuous mining machine is a self-propelled mining machine. It is provided at its forward end with cutting means shiftable in such a way that an entry is cut in the material being mined. The entry is so sized as to permit passage of the mining machine therethrough. Since the cutting operation is a continuous one, it is advantageous to provide means to move the cut material from in front of the mining machine and to convey it out of the entry.
One or several conveyors may be incorporated into the mining machine's construction that acts successively to transport the cut material rearwardly from the machine. One example of a conveyor that is incorporated into the mining machine extends from the front to the rear of the machine. The purpose of this conveyor is to remove the cut material from entry and deliver the cut material to other conveying means. The other conveying means may comprise mine cars or other vehicles used for hauling, portable belt conveyors or other conveyors designed for loading and unloading mined material from the mining machine, or the like.
An example of a conveyor that has been encountered in association with a continuous mining machine includes a section of conveyor base means mounted on the mining machine body. One or more additional sections of conveyor base means are connected thereto end-to-end, and extend beyond the rearward end of the mining machine body. All of the base means sections are characterized by a bottom portion provided with longitudinally extending, upstanding side guides or flanges. The various sections of the tail conveyor can be capable of both lateral and vertical movement with respect to each other, which enables the cut material to be delivered to a desired point despite changes of position of the mining machine as it advances in the entry and changes in level of the entry floor. The lateral and vertical movement capability of the conveyor sections may also enable the shifting of the desired delivery point for the material being mined, as required.
This type of conveyor may incorporate a continuous pusher-type conveyor chain, which is driven along the length of the conveyor base sections. The chain may be provided with a plurality of rigid pusher elements, normally extending substantially transversely of the conveying direction. The pusher elements are located at spaced intervals along the chain. Adjacent pusher elements may be joined together by a series of alternate block-like links and plate-like links. At one end of the machine's conveyor, the continuous chain passes over a driven sprocket. At the other end of the conveyor, the chain passes over a driven or idler sprocket, or roller.
Various embodiments of a conveyor chain configured to be used in conjunction with a dual drive sprocket on a mining machine are disclosed in the following applications: U.S. Provisional Patent Application No. 60/238,877, filed Oct. 6, 2000; PCT Patent Application Serial No. PCT/US01/31746, filed Oct. 9, 2001; and U.S. Nonprovisional patent application Ser. No. 10/398,387, which was filed on Apr. 7, 2003 and is now issued as U.S. Pat. No. 8,016,102; the disclosures of which are incorporated by reference herein.
Typically in the underground mining industry, machine downtime is very expensive. Should a conveyor chain fail (due to sudden impact or wear), the chain often would come apart during production causing several hours of expensive and unproductive downtime while the chain was repaired. Most often a conveyor chain fails from impact loads on the flight arms. These impacts over time cause a fracture which then causes the welded-in pins to fail.
Accordingly, it is desirable to provide a conveyor chain that has specific features and structures to provide a robust design which will not fail under rigorous usage.
The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.